If you design and implement APIs for a living then you’re probably already familiar with swagger. Swagger is a specification for defining API endpoints and the model objects they transact. Once you have a swagger definition of your API written in either json or yaml you can do quite a few useful things with it: generate HTML documentation on the fly; generate client and server code; generate a postman collection for endpoint testing; and more to the point of this piece, use the spec to validate incoming objects at request time, resulting in meaningful error responses to clients.